This performance statistic averages the difference (model - observed) over
Mean Bias (ppb):
all pairs in which the observed values were greater than zero. A mean bias of zero indicates that
the model over predictions and model under predictions exactly cancel each other out. Note that
the model bias is defined such that positive values indicate that the model prediction exceeds the
observation, whereas negative values indicate an underestimate of observations by the model.
This model performance estimate is used to make statements about the absolute or unnormalized
bias in the model simulation.
Normalized Mean Bias (percent): This statistic averages the difference (model - observed)
over the sum of observed values. Normalized mean bias is a useful model performance indicator
because it avoids over inflating the observed range of values.
Mean Fractional Bias (percent): Normalized bias can become very large when a minimum
threshold is not used. Fractional bias is used as a substitute. The fractional bias for cases with
factors of 2 under- and over-prediction are -67 and + 67 percent, respectively (as opposed to -50
and +100 percent, when using normalized bias). Fractional bias is a useful indicator because it
has the advantage of equally weighting positive and negative bias estimates. The single largest
disadvantage is that the predicted concentration is found in both the numerator and denominator.
Mean Error (ppb): This performance statistic averages the absolute value of the difference
(model - observed) over all pairs in which the observed values are greater than zero. It is similar
to mean bias except that the absolute value of the difference is used so that the error is always
n901 - n902 - n903 - n904 - n905 - n906 - n907 - n908 - n909 - n910 - n911 - n912 - n913 - n914 - n915 - n916 - n917 - n918 - n919 - n920 - n921 - n922 - n923 - n924 - n925 - n926 - n927 - n928 - n929 - n930 - n931 - n932 - n933 - n934 - n935 - n936 - n937 - n938 - n939 - n940 - n941 - n942 - n943 - n944 - n945 - n946 - n947 - n948 - n949 - n950
castellano: DISPER CUSTIC DESCAR RADIA italiano:
deutsch: DIS CUS DES RAD
castellano: DIS CUS DES RAD english: DIS CUS DES RAD
português: DIS CUS DES RAD italiano: DIS CUS DES RAD
français: DIS CUS DES RAD